Tracking the mind's image in the brain : combining evidence from fMRI and rTMS

Die Dissertation kombiniert die Methode der funktionellen Magnetresonanztomographie (fMRT) zur genauen räumlichen Lokalisation aufgabenkorrelierter parietaler Aktivierungen mit Transkranieller Magnetstimulation (TMS) zur systematischen Untersuchung der funktionellen Relevanz dieser Aktivierungen für die tatsächliche Leistungsfähigkeit. Die experimentelle Kombination beider Methoden ermöglichte die gezielte Stimulation der im tMRT identifizierten, mit visuospatialen Fähigkeiten assoziierten Hirnareale. Durch die systematische Auswertung der TMS-induzierten visuospatialen Leistungsveränderungen wurde die spezifische funktionelle Bedeutung dieser Hirnareale für visuospatiale Leistungen experimentell untersucht. Der zugrunde gelegte Versuchsplan umfasste sowohl visuospatiale Leistungen auf der Grundlage visuell dargebotener als auch mental vorgestellter Aufgaben. Dies ermöglichte die systematische Untersuchung, ob und inwieweit mentale visuospatiale Informationsverarbeitung die gleichen oder ähnliche Aktivierungsmuster im fMRT aufweist wie visuospatiale Verarbeitung visuell dargebotener Stimuli, und ob sich diese Aktivierungsmuster vorgestellter Stimuli unter dem Einfluss von rTMS in gleicher Weise als funktionell relevant erweisen. Aufgrund der separaten unilateralen Stimulation beider Hemisphären konnten darüber hinaus die unterschiedlichen behavioralen Auswirkungen einer Aktivierungsunterdrückung des linken und rechten Parietalkortex systematisch untersucht werden. Obwohl die Ausführung visuospatialer Aufgaben, sowohl auf der Grundlage visuell dargebotener als auch mental vorgestellter Stimuli, im fMRT mit einer bilateralen Aktivierung im Parietalkortex korrelierte, führte lediglich die TMS-induzierte temporäre Unterbrechung der neuronalen Aktivierung im rechten Parietalkortex zu einer signifikanten Verschlechterung in der Leistungsfähigkeit der damit assoziierten visuospatialen Aufgaben. Auf der Grundlage dieser Ergebnisse wurde ein modulares Modell der visuospatialen Imagination formuliert, in welchem den aufgabenkorrelierten bilateralen Aktivierungen aufgrund ihrer raum-zeitlichen Separierbarkeit unterschiedliche mentale Prozesse und aufgrund der mit TMS aufgezeigten funktionellen hemisphärischen Asymmetrie parietaler Aktivierung für visuospatiale Informationsverarbeitung unterschiedliche Kompensationsmechanismen zugeordnet wurden

Character Networks for Narrative Generation: Structural Balance Theory and the Emergence of Proto-Narratives

This paper models narrative as a complex adaptive system in which the temporal sequence of events constituting a story emerges out of cascading local interactions between nodes in a social network. The approach is not intended as a general theory of narrative, but rather as a particular generative mechanism relevant to several academic communities: (1) literary critics and narrative theorists interested in new models for narrative analysis, (2) artificial intelligence researchers and video game designers interested in new mechanisms for narrative generation, and (3) complex systems theorists interested in novel applications of agent-based modeling and network theory. The paper is divided into two parts. The first part offers examples of research by literary critics on the relationship between social networks of fictional characters and the structure of long-form narratives, particularly novels. The second part provides an example of schematic story generation based on a simulation of the structural balance network model. I will argue that if literary critics can better understand sophisticated narratives by extracting networks from them, then narrative intelligence researchers can benefit by inverting the process, that is, by generating narratives from networks

Hemispheric Differences within the Fronto-Parietal Network Dynamics Underlying Spatial Imagery

Spatial imagery refers to the inspection and evaluation of spatial features (e.g., distance, relative position, configuration) and/or the spatial manipulation (e.g., rotation, shifting, reorienting) of mentally generated visual images. In the past few decades, psychophysical as well as functional brain imaging studies have indicated that any such processing of spatially coded information and/or manipulation based on mental images (i) is subject to similar behavioral demands and limitations as in the case of spatial processing based on real visual images, and (ii) consistently activates several nodes of widely distributed cortical networks in the brain. These nodes include areas within both, the dorsal fronto-parietal as well as ventral occipito-temporal visual processing pathway, representing the “what” versus “where” aspects of spatial imagery. We here describe evidence from functional brain imaging and brain interference studies indicating systematic hemispheric differences within the dorsal fronto-parietal networks during the execution of spatial imagery. Importantly, such hemispheric differences and functional lateralization principles are also found in the effective brain network connectivity within and across these networks, with a direction of information flow from anterior frontal/premotor regions to posterior parietal cortices. In an attempt to integrate these findings of hemispheric lateralization and fronto-to-parietal interactions, we argue that spatial imagery constitutes a multifaceted cognitive construct that can be segregated in several distinct mental sub processes, each associated with activity within specific lateralized fronto-parietal (sub) networks, forming the basis of the here proposed dynamic network model of spatial imagery

Rethinking the role of sham TMS

Sham TMS approaches are widely used in basic and clinical research to ensure that observed effects are due to the intended neural manipulation instead of being caused by various possible side effects. We here critically discuss several methodological aspects of sham TMS. Importantly, we propose to carefully distinguish between the placebo versus sensory side effects of TMS. In line with this conceptual distinction, we describe current limitations of sham TMS approaches in the context of placebo effects and blinding success, followed by a short review of our own work demonstrating that the sensory side effects of sham TMS are not unspecific as often falsely assumed. Lastly, we argue that sham TMS approaches are inherently insufficient as full-fledged control conditions as they fail to demonstrate the specificity of TMS effects to a particular brain area or time point of stimulation. Sham TMS should therefore only complement alternative control strategies in TMS research

Innovationsinseln in korporatistischen Arrangements: Public Private Partnerships im Feld sozialer Dienstleistungen

Öffentlich-private Kooperationen im Sozialen Sektor sind ein altes und neues Phänomen. Der vorliegende Text gibt in dieser Spannung einen Überblick über die Entwicklung von Public Private Partnership in diesem Feld. Die Arena der personenbezogenen sozialen Dienstleistungen zeigt sich nach den Bereichen der Stadt- und Regionalentwicklung und der technischen Infrastrukturen als jüngster Sektor in Deutschland, in dem Public Private Partnerships (PPP) Bedeutung erlangen. Allerdings entstehen diese neuen Kooperationsformen innerhalb eines dichten Netzes korporatistischer Arrangements von staatlichen Institutionen und Dritt-Sektor- Organisationen. Zum jetzigen Zeitpunkt sind PPP lediglich vereinzelte neue Organisationsformen in diesem Feld. Aus der Dynamik der Interaktionsbeziehungen und Ressourcenkopplungen innerhalb dieser PPP können jedoch spezifische Qualitätsverbesserungen hervor gehen, die wir vor allem in der Integration von Aufgaben zu neuen lebenslagenorientierten Angeboten und in der Entwicklung höherer Dienstleistungsstandards sehen.In the Social Service Sector, public private cooperation is an old, but also a new phenomenon. The present study gives an overview of the development of public private partnerships in this area. The most recent sector in Germany, after those of urban development and technical infrastructure, in which public private partnerships (PPP) become relevant, is the arena of person-related social services. Such new forms of cooperation develop, however, within a dense network of corporatist arrangements between national institutions and Third Sector service organizations. To date, PPPs have only become sporadic new organizational forms in this field. Nevertheless, specific improvements in quality might emerge from the dynamics of inter-organisational relations and the linkage of resources within PPPs which, eventually, should lead to an integration of services which better consider specific personal circumstances and to the development of higher standards of social service

Interindividual variability and intraindividual reliability of intermittent theta burst stimulation-induced neuroplasticity mechanisms in the healthy brain

We combined patterned TMS with EMG in several sessions of a within-subject design to assess and characterize intraindividual reliability and interindividual variability of TMS-induced neuroplasticity mechanisms in the healthy brain. Intermittent theta burst stimulation (iTBS) was applied over M1 to induce long-term potentiation-like mechanisms as assessed by changes in corticospinal excitability. Furthermore, we investigated the association between the observed iTBS effects and individual differences in prolonged measures of corticospinal excitability. Our results show that iTBS-induced measures of neuroplasticity suffer from high variability between individuals within a single assessment visit and from low reliability within individuals across two assessment visits. This indicates that both group and individual effects of iTBS on corticospinal excitability cannot be assumed to be reliable and therefore need to be interpreted with caution, at least when measured by changes in the amplitudes of motor-evoked potentials.</p

Innovationsinseln in korporatistischen Arrangements: Public Private Partnerships im Feld sozialer Dienstleistungen

Öffentlich-private Kooperationen im Sozialen Sektor sind ein altes und neues Phänomen. Der vorliegende Text gibt in dieser Spannung einen Überblick über die Entwicklung von Public Private Partnership in diesem Feld. Die Arena der personenbezogenen sozialen Dienstleistungen zeigt sich nach den Bereichen der Stadt- und Regionalentwicklung und der technischen Infrastrukturen als jüngster Sektor in Deutschland, in dem Public Private Partnerships (PPP) Bedeutung erlangen. Allerdings entstehen diese neuen Kooperationsformen innerhalb eines dichten Netzes korporatistischer Arrangements von staatlichen Institutionen und Dritt-Sektor- Organisationen. Zum jetzigen Zeitpunkt sind PPP lediglich vereinzelte neue Organisationsformen in diesem Feld. Aus der Dynamik der Interaktionsbeziehungen und Ressourcenkopplungen innerhalb dieser PPP können jedoch spezifische Qualitätsverbesserungen hervor gehen, die wir vor allem in der Integration von Aufgaben zu neuen lebenslagenorientierten Angeboten und in der Entwicklung höherer Dienstleistungsstandards sehen. -- In the Social Service Sector, public private cooperation is an old, but also a new phenomenon. The present study gives an overview of the development of public private partnerships in this area. The most recent sector in Germany, after those of urban development and technical infrastructure, in which public private partnerships (PPP) become relevant, is the arena of person-related social services. Such new forms of cooperation develop, however, within a dense network of corporatist arrangements between national institutions and Third Sector service organizations. To date, PPPs have only become sporadic new organizational forms in this field. Nevertheless, specific improvements in quality might emerge from the dynamics of inter-organisational relations and the linkage of resources within PPPs which, eventually, should lead to an integration of services which better consider specific personal circumstances and to the development of higher standards of social service.

Automatic and Intentional Number Processing Both Rely on Intact Right Parietal Cortex: A Combined fMRI and Neuronavigated TMS Study

Practice and training usually lead to performance increase in a given task. In addition, a shift from intentional toward more automatic processing mechanisms is often observed. It is currently debated whether automatic and intentional processing is subserved by the same or by different mechanism(s), and whether the same or different regions in the brain are recruited. Previous correlational evidence provided by behavioral, neuroimaging, modeling, and neuropsychological studies addressing this question yielded conflicting results. Here we used transcranial magnetic stimulation (TMS) to compare the causal influence of disrupting either left or right parietal cortex during automatic and intentional numerical processing, as reflected by the size congruity effect and the numerical distance effect, respectively. We found a functional hemispheric asymmetry within parietal cortex with only the TMS-induced right parietal disruption impairing both automatic and intentional numerical processing. In contrast, disrupting the left parietal lobe with TMS, or applying sham stimulation, did not affect performance during automatic or intentional numerical processing. The current results provide causal evidence for the functional relevance of right, but not left, parietal cortex for intentional, and automatic numerical processing, implying that at least within the parietal cortices, automatic, and intentional numerical processing rely on the same underlying hemispheric lateralization

Probleme der Geldreform in den baltischen Staaten

http://tartu.ester.ee/record=b2418796~S1*es

When and How to Interpret Null Results in NIBS: A Taxonomy Based on Prior Expectations and Experimental Design

Experiments often challenge the null hypothesis that an intervention, for instance application of non-invasive brain stimulation (NIBS), has no effect on an outcome measure. In conventional statistics, a positive result rejects that hypothesis, but a null result is meaningless. Informally, however, researchers often do find null results meaningful to a greater or lesser extent. We present a model to guide interpretation of null results in NIBS research. Along a “gradient of surprise,” from Replication nulls through Exploration nulls to Hypothesized nulls, null results can be less or more surprising in the context of prior expectations, research, and theory. This influences to what extent we should credit a null result in this greater context. Orthogonal to this, experimental design choices create a “gradient of interpretability,” along which null results of an experiment, considered in isolation, become more informative. This is determined by target localization procedure, neural efficacy checks, and power and effect size evaluations. Along the latter gradient, we concretely propose three “levels of null evidence.” With caveats, these proposed levels C, B, and A, classify how informative an empirical null result is along concrete criteria. Lastly, to further inform, and help formalize, the inferences drawn from null results, Bayesian statistics can be employed. We discuss how this increasingly common alternative to traditional frequentist inference does allow quantification of the support for the null hypothesis, relative to support for the alternative hypothesis. It is our hope that these considerations can contribute to the ongoing effort to disseminate null findings alongside positive results to promote transparency and reduce publication bias